Munition Swarm Ranging to Constrain IMU Navigation Drift
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Solution Overview
Problem
In a GPS-denied environment, munitions relying solely on Inertial Measurement Unit (IMU) for navigation often experience navigational drift due to biases, leading to inaccurate target engagement and increased costs, overkill, or misses in target destruction.
Innovation Solution
Equipping each munition with Two-Way Timing and Ranging (TWTR) algorithms for estimating range and synchronizing onboard clocks via datalink communication, allowing munitions to share position estimates and range measurements to constrain IMU bias errors and maintain accurate navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If munitions rely solely on IMU for navigation in GPS-denied environment, then navigation autonomy is improved, but navigation accuracy deteriorates due to drift
Solution Approach 1:
The patent implements feedback by having munitions exchange position estimates and range measurements through datalink communication. Each munition uses the range measurements from other munitions to detect and correct drift in its own IMU integration, creating a closed-loop feedback system that maintains navigation accuracy without GPS
Solution Approach 2:
The patent introduces range measurements as an intermediary element between munitions. These range measurements serve as a mediator that allows munitions to indirectly observe and correct each other's navigation drift, enabling accurate relative positioning without direct GPS access
2Adaptability or versatility
If navigation solution drifts due to IMU bias, then navigation autonomy is maintained, but target engagement precision deteriorates
Solution Approach 1:
The system uses feedback from exchanged position estimates and range measurements to continuously monitor and correct navigation drift. This feedback mechanism ensures that target engagement precision is maintained by compensating for IMU bias accumulation during flight
Solution Approach 2:
The patent replaces reliance on purely mechanical inertial navigation with a hybrid system that uses electromagnetic datalink communication to exchange correction data. This substitution of mechanical inertial drift with electromagnetic communication-based correction maintains precision without sacrificing autonomy
3Reliability
If additional munitions are deployed to compensate for navigation drift, then target engagement reliability is improved, but operational cost increases
Solution Approach 1:
The feedback mechanism through datalink communication allows each munition to self-correct its navigation drift using information from other munitions in the salvo. This eliminates the need to deploy additional munitions as backup, maintaining target engagement reliability while reducing operational costs
Data Source
AI summary
A method and system for constraining navigational drift in a munition caused by Inertial Measurement Unit (IMU) bias error during flight of the munition in a constellation of a plurality of munitions in a Global Positioning System (GPS) denied attack. Each munition is provided with a datalink communication system to communicate with other munitions in the constellation and a navigation system having an IMU for guiding the munition in flight. An estimated position and covariance of the estimated position is determined for each munition via each munitions' navigation system. A range of each munition relative to at least one other munition in the munition constellation is determined via each munitions' datalink communication system. The estimated position and range to at least one other munition in the munition constellation is shared by each munition via each munitions' datalink communication system. Navigational drift for each munition is determined utilizing the estimated position of at least one other munition and the range to that at least one other munition in the munition constellation. And navigational drift in each munition is constrained by compensating for IMU bias error in each munition utilizing the determined navigational drift for each respective munition in the munition constellation.